JWT Expiration Checker
Inspect JWT exp, nbf, and iat claims and convert their NumericDate values to readable UTC without verifying the signature.
JWT Timing Result
JWT timing results will appear here.
Signature and Trust Limitation
Decoding happens locally in your browser. This tool does not verify the JWT signature, issuer, audience, revocation state, permissions, or application policy. A matching time window does not prove that the token is authentic or acceptable.
Inspecting JWT Timing Claims Without Calling the Issuer
JWT payloads can include NumericDate claims measured in seconds from the Unix epoch. The exp claim sets an expiry boundary,nbf sets a not-before boundary, and iatrecords when the token was issued.
This checker decodes those values and compares them with the current browser time. It is useful during API and session debugging, but it is not a substitute for server-side token verification.
How to Use the JWT Expiration Checker
- Paste a compact JWT with three dot-separated sections.
- Click Check Timing Claims.
- Review the current status and readable UTC values.
- Verify the signature and application-specific claims separately.
How Timing Is Interpreted
- exp: The token should not be accepted at or after this time.
- nbf: The token should not be accepted before this time.
- iat: Records issue time but does not by itself define validity.
- Clock skew: Real systems may allow a small configured tolerance.
Frequently Asked Questions
Does this verify the JWT signature?
No. It only decodes the payload and inspects timing claims. Use a verifier with the expected key and algorithm for signature checking.
Why can an expired token still be decoded?
JWT payloads are encoded, not encrypted by default. Expiry affects whether software should accept the token, not whether its payload can be read.
What happens when exp is missing?
The tool reports that no expiry boundary is available. Whether a token without exp is acceptable depends on the issuing system and application policy.
Can server time differ from browser time?
Yes. This tool uses your device clock. Production systems may use a different clock and may apply a small clock-skew tolerance.